1. Technical Field
The present invention relates to a display device and a projector, and, in particular to a projector capable of expressing a wide range of color gamut and for forming a protection image using four kinds of colored light.
2. Related Art
As the performance of a display apparatus is advanced, a technology for reproducing a life faithfully and with natural colors has been desired. A typical display apparatus uses a method of generating a color mage using colored light of the three primary colors, namely red colored light (R), green colored light (G), and blue colored light (B). However, partially because of restriction of a color filter or a fluorescent material, the method can only cover about a half of the color gamut perceivable to the human (on the basis of Munsell color chart). Therefore, in some cases, the colors displayed on a screen have a different cast from the life cast, thus the application field of the display apparatus is limited by itself. Therefore, development of a display apparatus capable of covering a broader range of color gamut had been desired.
Under the above circumstances, development of a so-called multi-primary color display, which increases the colored light from the three primary colors in the past to expand the expressible color gamut, has been activated (see, e.g., Non-patient Document 1 (Masahiro Yamaguchi, “Multi-primary Color Display,” Color Forum Japan '99 Proceedings, Four Associations Concerning Optics, November 1999, pp. 73-79). The same applies to projectors, which realize a large screen display by enlargedly projecting an image formed on small-sized light valves.
Further, Non-patent Document 2 (S. Roth, et al. 2005 SID int. Symp. Tech. Digest of Papers, pp. 1818-1821 (2005)) discloses a projector using four transmissive liquid crystal light valves. In this projector, it is arranged that by adding yellow light (Y), which can be modulated independently, to the three primary colors of light (R, G, and B) of the past, the expressible color gamut can be expanded about 1.45 times as large as that of the past, thus the cast of colors, which cannot be expressed by the projector of the past, can be expressed.
The projectors disclosed in the Non-Patent Documents 1 and 2 have the optical configurations of combining the three primary color light beams independently modulated by the three liquid crystal light valves, respectively, which are used in existing projectors, as the base configurations, and add the same liquid crystal light valve in the past thereon as the fourth light modulation means, thus realizing the multi-primary color display.
As described above, although the projector using the multi-primary color light beams has been realized in principle, as the number of liquid crystal light valves increases, the number of components also increases, thus the configuration of the optical system becomes problematically complicated. Therefore, the problem of difficulty in downsizing and cost reduction of the projector apparatus arises.